Technical Field
The present invention relates to a hydraulic circuit for a construction machine and a control device for the same.
Description of Related Art
Some construction machines perform a control (a bleed-off control) of returning a part (e.g., an excess) of a pressurized oil discharged from a hydraulic pump to an operating oil tank. In order to perform the bleed-off control, some construction machines have a gap (e.g., a bleed opening) for returning the pressurized oil in a spool of a directional control valve. According to, for example, the construction machine performs the bleed-off control by changing the opening area of the bleed opening.
An exemplary construction machine has multiple bleed openings Sbo in a spool of a directional control valve Vm as illustrated in FIG. 6. At this time, the hydraulic circuit performs the bleed-off control by changing the opening area of the bleed opening Sbo.